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Exchange 2010 CAS High Availability without NLB RRS feed

  • Question

  • Hello

    Can someone please enlighten me on the behavior of multiple Exchange 2010 CAS servers in a Non-NLB configuration? How is HA achieved? I’ve been trying to find a definitive answer to this question. What parametre would you have to configure to get HA without a NLB/array?

    Thanks

    Monday, January 24, 2011 7:24 PM

Answers

  • With no NLB or Hardware LB then there is no way to have high availability. You would still have to create a CAS Array, make the DBs use it for RpcClientAccessServer, and point the DNS A record to a single CAS server IP. Then if that CAS server were to fail or is going to be taken offline for maintenance you have to change the DNS record to point to another CAS server. It isn't very elegant. :)
    Microsoft Premier Field Engineer, Exchange
    MCSA 2000/2003, CCNA
    MCITP: Enterprise Messaging Administrator 2010
    Former Microsoft MVP, Exchange Server
    My posts are provided “AS IS” with no guarantees, no warranties, and they confer no rights.
    • Proposed as answer by Evan Liu Wednesday, January 26, 2011 8:44 AM
    • Marked as answer by Evan Liu Thursday, February 3, 2011 11:56 AM
    Monday, January 24, 2011 7:27 PM
  • Hi SamuraikJaacckk,

     

    Brian is right. If a CAS array exists in the AD site when you create a new mailbox database, the attribute “RpcClientAccessServer” will automatically be set to the FQDN of the CAS array.

     

    Configuring WNLB or Hardware Load Balancer can help you effectively balance the connections to the CAS servers in the AD site. But please note when you use Windows NLB with an Exchange 2010 DAG, you need to have the Client Access server role and Mailbox server role running on separate servers.

     

    You can get more information from the following documents:

     

    Understanding Load Balancing in Exchange 2010

    http://technet.microsoft.com/en-us/library/ff625247.aspx

     

    Understanding RPC Client Access

    http://technet.microsoft.com/en-us/library/ee332317.aspx

     

    Uncovering the new RPC Client Access service included with Exchange 2010

    http://www.msexchange.org/articles_tutorials/exchange-server-2007/planning-architecture/uncovering-new-rpc-client-access-service-exchange-2010-part1.html

     

    Best Regards,

     

    Evan

     

     


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.
    • Marked as answer by Evan Liu Thursday, February 3, 2011 11:57 AM
    Thursday, January 27, 2011 5:30 AM

All replies

  • With no NLB or Hardware LB then there is no way to have high availability. You would still have to create a CAS Array, make the DBs use it for RpcClientAccessServer, and point the DNS A record to a single CAS server IP. Then if that CAS server were to fail or is going to be taken offline for maintenance you have to change the DNS record to point to another CAS server. It isn't very elegant. :)
    Microsoft Premier Field Engineer, Exchange
    MCSA 2000/2003, CCNA
    MCITP: Enterprise Messaging Administrator 2010
    Former Microsoft MVP, Exchange Server
    My posts are provided “AS IS” with no guarantees, no warranties, and they confer no rights.
    • Proposed as answer by Evan Liu Wednesday, January 26, 2011 8:44 AM
    • Marked as answer by Evan Liu Thursday, February 3, 2011 11:56 AM
    Monday, January 24, 2011 7:27 PM
  • If you don’t use NLB you are going to purchase a hardware load balancer. DNS RR doesn’t exactly quite count as CAS HA.
     
     
    "SamuraikJaacckk" wrote in message news:cfc8556d-0649-4dfc-818a-87fbfad5b93b...

    Hello

    Can someone please enlighten me on the behavior of multiple Exchange 2010 CAS servers in a Non-NLB configuration? How is HA achieved? I’ve been trying to find a definitive answer to this question. What parametre would you have to configure to get HA without a NLB/array?

    Thanks


    Mark Arnold, Exchange MVP.
    Monday, January 24, 2011 7:27 PM
  • I was really hoping for a more elegant solution. if the cas servers are cas1 and cas2, when i create the cas array call it casarray1 do i need to do anything special with the databases usng the rpcclientaccesserver tag? how does this scenario work in a DAG?
    Wednesday, January 26, 2011 7:01 PM
  •  

    Any mailbox database created in the same AD site as the CAS Array created after the CASA Array is created will automatically put CASArray1 in the RpcClientAccessServer field.

    Creation of a CAS Array doesn't do any kind of load balancing, it just makes the RpcClientAccessServer attribute get populated. You then have to configure WNLB, or a Hardware Load Balancer to actually balance the connections across the CAS servers in that AD site.


    Microsoft Premier Field Engineer, Exchange
    MCSA 2000/2003, CCNA
    MCITP: Enterprise Messaging Administrator 2010
    Former Microsoft MVP, Exchange Server
    My posts are provided “AS IS” with no guarantees, no warranties, and they confer no rights.
    Wednesday, January 26, 2011 8:12 PM
  • Hi SamuraikJaacckk,

     

    Brian is right. If a CAS array exists in the AD site when you create a new mailbox database, the attribute “RpcClientAccessServer” will automatically be set to the FQDN of the CAS array.

     

    Configuring WNLB or Hardware Load Balancer can help you effectively balance the connections to the CAS servers in the AD site. But please note when you use Windows NLB with an Exchange 2010 DAG, you need to have the Client Access server role and Mailbox server role running on separate servers.

     

    You can get more information from the following documents:

     

    Understanding Load Balancing in Exchange 2010

    http://technet.microsoft.com/en-us/library/ff625247.aspx

     

    Understanding RPC Client Access

    http://technet.microsoft.com/en-us/library/ee332317.aspx

     

    Uncovering the new RPC Client Access service included with Exchange 2010

    http://www.msexchange.org/articles_tutorials/exchange-server-2007/planning-architecture/uncovering-new-rpc-client-access-service-exchange-2010-part1.html

     

    Best Regards,

     

    Evan

     

     


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.
    • Marked as answer by Evan Liu Thursday, February 3, 2011 11:57 AM
    Thursday, January 27, 2011 5:30 AM